Spatial variability of carbon stocks in the Coastal Tablelands of Paraiba state, Brazil: Soil cultivated with sugarcane

Abstract

Estimates of carbon stocks in Brazilian soils are few and difficult to obtain due to the lack of information on the amount of soil organic carbon under  different uses and in different regions. The aim of this study was to evaluate the carbon stocks and its spatial variability in an Ultisol cultivated with
sugarcane. The study was carried out in a 790 ha area in the surroundings of municipality of Capim, Paraíba State, Brazil. A 300 x 400 m grid was projected onto the experimental area. Soil samples were obtained at each grid point (68 points) in three depths in accordance with the natural topography of the area. The data set was submitted to descriptive statistics, geostatistics and kriging analyses. The coefficient of variation indicated medium variability at depths 0 – 30 and 30 – 63 cm and high variability in 63 – 100 cm depth. Moderate spatial dependence was observed in the surface layer and strong spatial dependence at the depths of 30 – 63 and 63 – 100 cm. The carbon stock in the surface layer was, on average, 33.82 Mg ha^-1, whereas in the other layers were 26.37 and 21.21 Mg ha^-1, respectively. The geostatistic analysis allowed a description of soil carbon stocks which permitted the definition of site-specific management.